Peru said on Monday that it may seek the extradition of members of environmental group Greenpeace for causing "irreparable" damage to the Nazca Lines - giant designs mysteriously etched into the sand and preserved for more than 1,500 years.

The activists left Peru after leaving behind a trail of footprints in a delicate stretch of desert near the iconic Nazca figure of a hummingbird, where they spelled "Time for change!

The future is renewable" in large cloth letters, said Culture Minister Diana Alvarez-Calderon.

The message, on a protected UNESCO world heritage site, aimed to pressure negotiators at a United Nations climate change summit in Lima that ended on Sunday.

But the stunt backfired - angering not just Greenpeace's usual detractors but also archaeologists, environmentalists and a broad cross-section of Peruvians.

Last week a Peruvian judge rejected prosecutors' request to keep the activists in the country to face questioning, citing incomplete information.

But Alvarez-Calderon said authorities will keep trying to hold accountable the dozen activists involved in the action.

"The damage caused is irreparable," Alvarez-Calderon said at a news conference. "We have to continue the process when a person is not in Peru - extradition if the judge decides so or civil reparation."

Greenpeace apologized for the stunt last week and said it would take responsibility for the consequences of its actions.